On September 27th at Town Hall, Dr. Brett Finlay, talks about the subject of the new book he co-authored:"Let Them Eat Dirt: Saving Our Kids from an Oversanitized World." Finlay, a professor of Biochemistry & Molecular Biology and Microbiology & Immunology at the University of British Columbia who spent 30 years studying the bacteria of infectious disease, has now turned to exploring how bacteria is essential for our health. His and Marie-Claire Arrieta’s book about their research comes out this month. We talked to Dr. Finlay about his findings:

Seattle's Child: You've written a book about why dirt is good for us.

Brett Finlay: Well, it’s why microbes are good for you and there are microbes in dirt, so it’s not so much about the dirt as about raising our kids to have healthy microbes. Healthy microbes are absolutely essential for setting up healthy bodies. For example, you can make animals that are culture-free — they have no microbes — and their brain doesn’t develop normally, their gut doesn’t develop normally. We know these microbes play a major role in susceptibility to asthma, obesity and diabetes. And the theory is that in the last 50 years we’ve really worked hard to clean up our world, and now kids aren’t getting exposed to the microbes they used to get exposed to, including the good ones, so they don’t develop normally.

Were the hygienic people wrong, then?

No, they’ve done a spectacular job in cleaning up infectious diseases. But I think there are these unintended consequences. For instance, antibiotic use increases your rates of asthma, obesity, depression, anxiety and stress, because it carpet-bombs all the microbes. Our general lifestyle of washing our hands 45 times a day with hand cleanser — that’s not how we evolved as a species. We are used to living with our microbes, and suddenly we are denying our bodies that chance. So it screws up how we get set up early in life and has later effects.

So you suggest letting kids get dirtier and going outside more?

Obviously, you don’t go play in a sewage lagoon. There’s common sense to this. But I do think we need a generational change in how we think of our kids. If you watch a child in action, what do they do? A toddler, they put everything in their mouth, right? This is how we evolved as a species for a million years. So what if the kids are up to their armpits in mud? That’s what showers are for.

Interesting. So the first five years are the most critical time for exposure to microbes?

Yeah, that’s when your microbes are setting up. It’s actually the first 100 days that are by far the most critical window. Just the simple
fact of whether you are born by Cesarean section or vaginal birth has a 20 percent difference rate in your chances of getting asthma and allergies later in life. Of course vaginal is better, because you’re getting your mother’s microbes on the way out.

What about people who have missed that window?

Diet is a major thing. Fermented foods and fiber, and probiotics — those are the areas you can push a lot of microbes down into the gastrointestinal tract in a hurry.

Do you have any advice for how to get kids exposed to the good microbes without the bad ones?

Well, the good news is the world we live in is actually amazingly safe as far as bacterial pathogens. And the other thing is we have immune systems, and especially if there are healthy microbes, they are generally pretty good at fighting off these things. I’m not saying start licking the floor of the mall, but we need to think how we evolved as a species and how we live now. We do everything in our way not to let kids be kids, and maybe that needs a little rethink.